I don't recall hearing the message before, but I'll take your word for it that it's pre-existing. It sounds like the bigger issue is switches rather than station stops.
It sounds like the message is superfluous for the non-tilting Siemens trains, but if they insist on keeping the message, it should ideally be related to when the train is about to switch tracks, rather than when it's approaching a station. I realize that that's probably not practical to automate with our current line-of-sight signalling system, but once we install some form of ATP, the train would know the current signal indication and it would be possible to play a relevant message when the train receives a diverging indication. That way you wouldn't need to play the message at stations like Dorval where the train just pulls straight in, and you would play the message when the train switches tracks away from a station.
Allowing passengers to get up before the train stops can make a big difference to dwell times. One example comes to mind:
I was on a train heading eastbound toward Toronto, approaching Brampton 20+ minutes late. At this stop, only one group of passengers was alighting and nobody was boarding. A few minutes after the usual 10-minutes to arrival announcement, an attendant informed them personally that the train would be arriving in Brampton in a couple minutes. They didn't say that they should get up, but I'm guessing that was the implication. In any case, the group remained seated until the train came to a complete stop. Then they got up, walked all the way down to the end of the car to collect their bags, and eventually made their way to the door. In total we must have been stopped for over two minutes waiting for these 4 people to exit. If they'd gotten up and collected their bags before the train stopped, we could have been moving again within about 30 seconds.